Technical Field
Embodiments of the invention relate generally to controlling accessories. Other embodiments relate to a system and method for controlling electrically driven accessories.
Discussion of Art
In the mining industry, large off-highway vehicles, “OHVs”, usually employ electrically motorized wheels for propelling or retarding the vehicle. In particular, OHVs typically include a large horsepower diesel engine in conjunction with an alternator, a main traction inverter, and a pair of wheel drive assemblies housed within the rear tires of the vehicle. The diesel engine drives the alternator, which powers the main traction inverter. The traction inverter includes semiconductor power switches that commutate the alternator output current to provide electrical power to electric drive motors, e.g., AC motors, of the wheel drive assemblies.
Similarly, trains typically feature a number of cars that are pushed or pulled by a locomotive that utilizes electric wheel motors to drive traction wheels. The electric wheel motors are powered via electrical distribution from one or more engine-driven generators housed within the locomotive.
In both OHV and rail applications, solid-state power converters are used to provide high voltage current from the generators or alternators to wheel drive motors. Such power converters include inductive coils to step down the voltage as well as semiconductor power switches to commutate the current. In such systems, cooling of vehicle drive components may be accomplished through the use of electrically driven cooling systems that include blowers or fans. It may be possible, however, for communication between electrical components within an electrically driven cooling system to be interrupted or severed. As will be appreciated, if communication is lost, the system controller may not be able to control the cooling system resulting in a potentially immobile vehicle.
It is therefore desirable to provide a system and method for powering accessories, such as electrical cooling system, that allows for control of the accessory, e.g., a blower, in the event of a communication failure.